Washington’s revolving door is often used as a pejorative, but Mary Jo White said it’s personally helped her improve the Securities and Exchange Commission’s policing of Wall Street.

Ms. White, who became chairman of the SEC in April, said Thursday her prior legal work representing large banks and securities firms was “invaluable” in laying out a tougher enforcement policy that includes the pursuit of admissions of wrongdoing against companies and individuals in certain cases.

“I realized just how much leverage the SEC has,” Ms. White said, speaking at the Women, Influence & Power in Law summit in Washington. Many public companies would sooner acquiesce to a demand for an admission than engage in a long-running dispute with the agency, she suggested.

“You don’t want to be at war with your main regulator,” she added, saying the policy shift takes advantage of “perhaps more leverage than the SEC realized that it has.”

Ms. White has said the agency would, in select cases, insist on admissions of guilt as a condition in settlements of egregious misconduct, widespread harm to investors or where public accountability is important. That marks a shift from a long-established practice of allowing companies to settle allegations without admitting wrongdoing.

Ms. White formerly oversaw the litigation practice at Debevoise & Plimpton LLP, a New York white-shoe law firm where her clients included J.P. Morgan Chase & Co., Prudential Financial Inc. and General Electric Corp.

In one of the first examples, J.P. Morgan admitted it broke the securities laws as part of its $200 million settlement with the agency last month over a trading blunder that cost the bank more than $6 billion. Because of her prior work representing the bank, Ms. White was recused from the case. J.P. Morgan paid $920 million to 4 regulators as part of the settlement.